Doffing apparatus and method

ABSTRACT

A spinning frame has a plurality of stations for spinning roving into yarn and winding the yarn onto a bobbin. A tender moves passed the stations and stops at any of the stations requiring servicing such as, for example, doffing a filled bobbin and donning an empty bobbin. The tender then continues patrolling the stations until it comes upon another station requiring servicing. As the tender patrols the stations, a first sensing device on the tender scans the stations to determine whether or not the yarn is advancing normally and provides an appropriate signal. A signal from a second sensing device indicates whether or not the station is operational. The signal from the first sensing device is combined with the signal from the second sensing device to stop the tender only at an operational station requiring servicing, whereupon the servicing cycle commences. At the end of servicing, if the yarn is advancing normally the tender resumes its patrolling. If the yarn is not advancing properly, another servicing cycle is commenced. Thereafter, if the yarn is still not advancing properly, the roving is automatically broken above the usual drafting rolls of the station as a signal flag is positioned to indicate to the second sensing device that the particular station is non-operational. The tender is not stopped at a non-operational station. The two sensors may both be phototransducers. The first sensor provides a particular fluctuating signal responsive to a transverse alternating motion of the yarn which results from ballooning of the yarn as it is advanced longitudinally while being wound onto the bobbin, and this signal results in the tender passing the station and continuing its patrolling. All other fluctuating signals from the first sensor, such as may be caused by ambient light, either day light or artificial light, for example, as well as signals resulting from movement of the tender while patrolling the stations, are filtered out.

United States Patent Whitney 51 June 27, 1972 [54] DOFFING APPARATUS ANDMETHOD [72] Inventor:' William R. Whitney, Cranston, R.1.

[73] Assignee: Leesona Corporation, Warwick, RJ.

[22] Filed: Oct. 20, 1970 [21] Appl. No.: 82,455

[52] US. Cl. ..57/53, 57/34 R, 57/81, 57/156 [51] Int. Cl. ..D01h 9/10[58] Field ofSearch ..57/34 R,53, 156,81; 242/37 R, 35.5, 35.6

[56] References Cited UNITED STATES PATENTS 2,716,004 8/1955 Reiners etal. ..242/37 3,373,551 3/1968 Gillon et a1. ..57/34 PrimaryExaminer-Wemer 1-1. Schroeder Attorney-Albert P. Davis and Burnett W.Norton [57] ABSTRACT A spinning frame has a plurality of stations forspinning roving into yarn and winding the yarn onto a bobbin. A tendermoves passed the stations and stops at any of the stations requiringservicing such as, for example, doffing a filled bobbin and donning anempty bobbin. The tender then continues patrolling the stations until itcomes upon another station requiring servicing. As the tender patrolsthe stations, a first sensing device on the tender scans the stations todetermine whether or not the yarn is advancing normally and provides anappropriate signal. A signal from a second sensing device indicateswhether or not the station is operational. The signal from the firstsensing device is combined with the signal from the second sensingdevice to stop the tender only at an operational station requiringservicing, whereupon the servicing cycle commences. At the end ofservicing, if the yarn is advancing normally the tender resumes itspatrolling. if the yarn is not advancing properly, another servicingcycle is commenced. Thereafter, if the yarn is still not advancingproperly, the roving is automatically broken above the usual draftingrolls of the station as a signal flag is positioned to indicate to thesecond sensing device that the particular station is nonoperational. Thetender is not stopped at a non-operational station. The two sensors mayboth be phototransducers. The first sensor provides a particularfluctuating signal responsive to a transverse alternating motion of theyarn which results from ballooning of the yarn as it is advancedlongitudinally while being wound onto the bobbin, and this signalresults in the tender passing the station and continuing its patrolling.All other fluctuating signals from the first sensor, such as may becaused by ambient light, either day light or artificial light, forexample, as well as signals resulting from movement of the tender whilepatrolling the stations, are filtered out.

17 Claims, 8 Drawing Figures PATENTEU JUN 2 7 1212 SHEET 10F 2 26 1]FlG.l

INVENTOR WILLIAM R. WHITNEY FIGZ ATTORNEYS WENIEBJUW 1272 3,672,143

SHEET 2 or 2 k A l/Ol IOI '0' 9* FIG. 5

IOG

F I e. 6

FIG. 8 F G 7 INVENTOR.

WILLIAM R. WHITNEY ATTORNEYS DOFFING APPARATUS AND METHOD This inventionrelates to a dofling apparatus and method and, more particularly, tosuch apparatus and method for dofimg strand processing equipment.

The following Leesona Corporation patents and patent applications are ofinterest and are incorporated by reference: US. Pat. No. 3,403,866,granted Oct. 1, 1968; U.S. Pat. No. 3,449,902, granted July 7, 1969; andU.S. Pat. No. 3,498,039, granted Mar. 3, 1970; and cospending US. patentapplications Ser. No. 884,960, filed Dec. 15, 1969; and Ser. No.877,678, filed Nov. 18, 1969.

As used herein the term yarn" means any strandular material, whethertextile or otherwise; the term bobbin" is used in a general sense toinclude anything on which yarn may be wound, such as a bobbin core,either filled or partially filled with yarn; and the term signal" meansthe presence or absence of a transmission.

Automatic operation of a spinning or twisting machine is disclosed inthe previously noted Leesona corporation US. Pat. No. 3,403,866 which isdirected to a servicing tender for patrolling or scanning a series ofbobbin winding stations of the machine. The tender includes a controlsystem for initiating servicing of any station requiring attention. Moreparticularly, the tender stops at a station to doff a full bobbin, or inthe event of disruption of the advancing strand of yarn to the bobbin,to remove the partially filled bobbin, and in either event then donns anempty bobbin core and initiates winding of the strand onto the core.Should the tender be unable to adequately service the station, thestation is rendered nonoperational and thereafter the tender by-passesthe station until the station is again placed in operational condition.

Another previously noted Leesona Corporation U.S. Pat. No. 3,498,039discloses an optical electronic control system for the tender. Thecontrol system has a phototransducer responsive to an indicator at eachstation for providing an operational signal when the station is inoperational condition and other phototransducers for providing aservicing signal when the station requires servicing, either because thebobbin is fully wound and requires doffing, or because of aninterruption in the strand along the path to the bobbin. Responsive tothese two signals, a work cycle of the tender is initiated. Ifthe tenderis unable to adequately service the station, it automatically operates aroving breaker which breaks the roving upstream of drafting rolls of thestation. In its normal or operational position, the roving breakerserves as the indicator for the operational signal and when in itsstrand breaking position the operational signal is not provided.

While interruption of the advancing strand, as by a break in the strand,has been detected as noted above, a stationary or fluttering strand hasnot been entirely satisfactorily differentiated from a normallyadvancing strand.

The invention is, in brief, directed to a doffing apparatus and methodfor strand processing equipment including at least one station at whichnormal longitudinal advancement of a strand is accompanied by atransverse motion of the strand and responsive to not sensing thetransverse motion, servicing of the station is regulated. Servicing isprovided by a patrolling tender, and following servicing of a station,patrolling of the tender is resumed. If the servicing attempt isunsuccessful, the station is rendered non-operational and patrolling ofthe tender is resumed. Sensors on the patrolling tender scan thestations and if a station is operational and requires servicing acontrol system responsive to the sensors causes the tender to stop atthe station requiring servicing. One of these sensors provides a signalindicating whether or not a station is operational and this signal isused in conjunction with a fluctuating signal responsive to thetransverse motion of the strand, for regulating operation of the tender.

It is a primary object of this invention to provide a new and improveddoffing apparatus and method.

Another object is provision of a new and improved doffing apparatus andmethod for strand processing equipment with provision for normallyadvancing a strand onto a bobbin at a station, provision for dofifingthe bobbin at the station, and provision for sensing whether or not thestrand is advancing at the station and responsive thereto controllingdofi'mg of the bobbin at the station. A related object is provision fornormally longitudinally advancing the strand at the station andconcurrently therewith imparting to the strand a particular range oftransverse alternating motion, sensing whether or not the strand isadvancing by providing various outputs and responsive to theaforementioned transverse motion of the strand providing a particularone of the outputs for regulating doffing of the station. Anotherrelated object is provision of a plurality of such stations and,provision for scanning the stations and responsive to the variousoutputs controlling doffing of the bobbin at the station being scanned.Further related objects include: providing the particular output in theform of a particular fluctuating signal, passing the particularfluctuating signal and responsive thereto providing a signal for doflingof the bobbin at the particular station; provision for determiningwhether ornot the strand is in operational condition to be advanced andwhen the strand is in such condition providing another signal, andresponsive to receiving both the operational signal and the particularfluctuating signal, by-passing doffing of the station; and apparatushaving a phototransducer for scanning the stations and providing thefluctuating signal, the phototransducer having either: only onephotosensitive area for receiving an image of the transverse motion ofthe strand to provide the fluctuating signal, or a photosensitive areahaving a plurality of particular photosensitive areas of greatersensitivity than intervening areas,or a plurality of discretephotosensitive areas for receiving an image of the transverse motion ofthe strand, such areas receiving at most the,

image of only a limited portion of the transverse span of motion of thestrand.

These and other objects and advantages of the invention will be apparentfrom the following description and the accompanying drawings, in which:

FIG. 1 is a fragmentary, schematic plan view. of a preferred embodimentof a spinning machine, with parts broken away and removed, generally asindicated along the line 1-1 in FIG. 2;

FIG. 2 is a fragmentary sectional view taken generally along the line2-2 in FIG. 1;

FIG. 3 is a fragmentary sectional view taken generally along the line3-3 in FIG. 2;

FIG. 4 is an electrical diagram of. a portion of a control system forthe machine;

FIGS. 5 and 6 are facial views of phototransducers which may be providedin the control system;

FIG; 7 is a wave form graph; and

FIG. 8 is an electrical diagram of a portion of another control systemfor the machine.

Referring to FIG. 1 of the drawings, a spinning frame 10 includes a base12 on which a series of spindles 14 are suitably joumaled and rotated,one at each of a plurality of stations 16. Each spindle l4 removablymounts a bobbin core telescoped on the spindle and on which a strand ofyarn is wound to form a package such as a bobbin 18.

As is more fully discussed in the aforementioned U.S. Pat. No.3,403,866, in order to scan the bobbins l8 and to service stations 16requiring attention, a pair of parallel tracks 20 are mounted on thebase 12 and receive wheels 22 of a tender in the form of a carriage 24mounted to traverse back and forth on the tracks past the stations 16.The carriage wheels 22 are suitably joumaled on a carriage body 26 and,more particularly, a pair of the wheels 22 at the right end of thecarriage body 26 are fixedly mounted on a shaft 28 received in journals30 on the carriage body. This shaft has fixed thereto a driven pulleywheel 32 connected by a timing belt 34 with a drive wheel 36 of asuitable reversible air motor 38 mounted on the carriage body 26. As thecarriage 24 moves toward the right end of its tracks 20, a pivotedactuator 40 of a switch 42 mounted on the carriage body 26 engages anabutment 44 on the base 12 to reverse the position of the switchactuator 40 and thereby the direction of the carriage 24, and at theleft end of the tracks 20 the actuator 40 engages another abutment 46 toagain reverse the carriage. The switch 42 is connected in circuit (FIG.4) with a four-way solenoid valve 48 so that when the switch actuatorengages one of the abutments, the solenoid valve is energized to reverseoperation of the motor 38, and when the switch actuator engages theother of the abutments, the solenoid valve is taken out of circuit toagain reverse the direction of operation of the air motor, thus causingthe carriage 24 to traverse to and fro past the bobbins 18 being woundat the stations 16.

During normal operation of the machine, roving 49 (FIG. 2) advancesdownwardly through a trumpet guide 50 and a set of drafting rolls 52,then past an inlet in a vacuum duct 54 for receiving and removing theroving in the event of breakage downstream of the drafting rolls. Theroving 49 is spun into yarn 55 and the yarn passes through a lower yarnguide 56 centered above the bobbin 18 and the rotating spindle l4, andfrom the lower guide 56 the yarn passes through a traveler 58 on a ring60 encircling the bobbin l8 and mounted on a ring rail 62 (FIG. 2) whichmoves up'and, down as the yarn 55 is advanced from the traveler 58 andis wound onto the bobbin. The parts 50-54 and 56-62 are all suitablymounted on the base 12.

As the yarn is advanced longitudinally it has imparted to it aconcurrent transverse oscillatory movement or balloon 62 (FIGS. 2 and 3)between the drafting rolls and the lower guide. This oscillatorymovement provides an image having a transversely alternating motion. Thefrequency and amplitude of the alternating motion will vary depending onthe amount of yarn wound on the bobbin.

In keeping with established practice, the trumpet guides 50 at eachstation are mounted on a horizontally movable bar 63 which is usuallyautomatically reciprocated, as indicated by the arrow 63A in FIG. 3, sothat the roving 49 is moved to and fro across the drafting rolls toavoid grooving the rolls.

If the station 16 is in operational condition, an indicator in the formof a roving breaker 64 is in an operational position as indicated by thesolid lines in FIG. 2. The roving breaker 64 is pivoted at its lower endto a suitable fixed support 66 of the machine and carries suitablemeans, such as a plurality of pins 68, for engaging the roving 49 abovethe trumpet guide 50 when the roving breaker 64 is pivoted to a positionagainst a frame member 70 as indicated by dotted lines in FIG. 2.Movement of the roving breaker 64 from its operational to itsnon-operational position may be effected in any suitable manner, and asillustrated in FIG. 2 is effected by opening a shutoff valve 72 toproject a jet of air from a tube 74 fixed on the carriage body 26 andaligned with the roving breaker in its operational position, with thecarriage in its servicing position at a station. Opening of the valve 72may be controlled in any desired manner, for example by a suitablesignal as disclosed in the aforementioned U.S. Pat. No. 3,403,866.

As the carriage 24 is moving past a station 16, an opera tional signalis provided by a suitable phototransducer unit 76 fixedly mounted on thecarriage body 26 and energized by a ray of light 78 originating from asuitable lamp 80 fixed on the carriage body and reflected off of theroving breaker 64 when the roving breaker is in its operational positionas shown by solid lines in FIG. 2. This signal, combined with aservicing signal starts the work cycle of the carriage 24. The servicingsignal may be provided either by a second or advancing yarnphototransducer unit 82 fixed on the carriage body 26 and receiving aray of light 84 from a lamp 86 fixed on the carriage body and reflectedoff of the advancing and therefore ballooning yarn 55 at a point betweenthe drafting rolls 52 and the lower yarn guide 56 and passing through asuitable lense unit 87 to provide a strand interruption signal, or by afull bobbin signal from a phototransducer assembly (not shown) fixed tothe carriage body 26, as is more fully described in the previously notedpatent application Ser. No. 877,678.

Referring to FIG. 4, the operational signal phototransducer unit 76 isconnected through an amplifier 1A with a relay IR and upon energizationof this unit a normally open switching means, such as a contact 1R1 ofthe relay 1R closes. If the roving breaker 64 is in its non-operationalposition, as shown by dotted lines in FIG. 2, the operational signalphototransducer unit 76 is not energized and the relay contact 1R1remains open.

When the yarn 55 is advancing properly to the bobbin, the advancing yarnphototransducer unit 82 provides a servicing signal (to be describedlater) which is received by a circuit, to be described later, andthrough a resultant control signal a relay 2R is energized and opens itsnormally closed switching means, such as a contact 2R1, which is inseries with the contact 1R1. If the contacts IR] and 2R1 are closed, astarting signal is provided to a control unit 96 of the carriage 24causing the carriage to stop at the station 16 requiring service and toproceed with servicing of the station, as described in the previouslymentioned U.S. Pat. No. 3,403,866. Otherwise, if either contact 1R1 or2R1 is open, the carriage continues its patrolling operation and passesthe station.

The portion of the control system for determining whether or not theyarn is advancing properly to the bobbin includes the previously notedphototransducer unit 82 which may be a plurality of phototransducers(FIGS. 1-5) or a single phototransducer unit 98 (FIG. 6). As shown inFIGS. 4 and 5, a plurality of (four) phototransducers, 100, each havinga sensitive area 101, pass various outputs or servicing signals to an ORgate 102 from which the signals pass to a filter 104. The filter pasesonly a particular one of the signals to an electronic switch 106 which,upon receiving the particular control signal, energizes the relay 2R toopen its normally closed contact 2R1.

If only one phototransducer 98 is provided, as in FIG. 6, the OR gatemay obviously be eliminated from the circuit, but the remainder of thecircuit remains the same as is shown in FIG. 4. The phototransducer unit98 has but one photosensitive area 108, but this area has a plurality of(four) generally parallel and interconnected portions 110 of greatersensitivity than the intervening areas 112. The portions 110 aretransverse, and preferably normal to the path of the tender.

In FIG. 7 the upper curve shows components of the servicing signal froma normally advancing and ballooning yarn 55, and these components arepassed by the filter 104. The lower curve shows a typical signal from astationary yarn, and this signal is not passed by the filter.

In a typical mill installation, light strikes the phototransducer unitfrom many sources. This light may be sunlight or artificial light,either direct or reflected from various parts of the apparatus. Sunlightand artificial illumination operated from direct current does notfluctuate in intensity. Most mill illumination uses 60 cycle per secondalternating current which causes the ambient light intensity tofluctuate times per second.

In order to generate a fluctuating signal which can bediscriminatedagainst the ambient background, the width of the sensitivearea 101 (FIG. 5) of each phototransducer 100 and the spacing betweenthe sensitive areas, in the direction of movement of the unit 82, mustbe smaller than the optically projected width of the smallest diameterof the balloon 63 observed by the sensitive areas 101. The maximum widthis equal to the product of the minimum balloon diameter times themagnification ratio of the optical system. For a minimum diameter ofthree thirty-second inch and a magnification ratio of H3, the maximumwidth is one thirty-second inch. If the traveler is rotating at 200r.p.s. and the image of the yarn is projected on the transducer for lessthan its full width and then returns over the same path, the output willbe equal to the traveler rotation rate or 200 pulses per second. If theimage is projected so that it completely traverses the phototransducerand goes into the insensitive area and then returns across thetransducer sensitive area, again the output will fluctuate at a ratedouble that of the traveler rate or 400 pulses per second.

In FIG. 8 a simplified phototransducer portion of the FIG. 4 circuit isdiagrammed for a tender preferably having a lineal speed as itapproaches a station of 9 inches per second. Therein, a phototransducerunit 114 has but one transducer with a single sensitive area smallerthan the smallest normally possible balloon 63, as previously discussed.If desired the unit 114 may have a plurality of sensitive areas, aspreviously described. The unit 114 may be a Motorola MRD 150phototransistor, and is connected in the circuit as shown, in which: aDarlington Amplifier configuration 118 is General Electric part No.2N5306; and transistors 120 and 122 are General Electric part No. 2N5354 and 2N5027, respectively; resistors 124 are 0.5M; resistors 126 arelOM; resistor 128 is 16.8K; and resistors 130 are 6.8K; and capacitors132 are 0.1MFD; and capacitor 134 is 4MFD. A power supply of 12-14 voltsD.C., for example, is provided between connectors 136 and 138 and acontrol or output signal is provided between connectors 138 and 140.

The phototransducer unit (82 or 98) will provide various outputs orfluctuating signals from the various sources of light which may bereflected from the advancing yarn or other parts of the equipment, butonly the particular output within a particular frequency and amplituderange, resulting from the image reflected from the ballooning yarn willbe passed by the filter for actuating the electronic switch to stop thetender and start servicing of the station.

When a first servicing cycle at a station is completed and the yarn isadvancing normally, the phototransducer unit again provides theparticular signal whereupon the relay 2R is energized and opens itscontact 2R1 to drop the control unit out of circuit and the carriageresumes its patrolling. As the carriage moves on, the operationalphototransducer unit moves away from its roving breaker target and therelay IR is, taken out of circuit, opening its contact 1R1 which remainsopen until another target causes the cycle to be repeated. As describedin the previously noted patent, U.S. Pat. No. 3,403,866, if the firstservicing cycle was not successful, the control unit cause the servicecycle to be repeated, and if the yarn is still not advancing normally tothe bobbin after the second cycle, the control unit causes the rovingbreaker to break the roving, and causes the tender to continue itspatrolling and scanning of the stations and to by-pass any station onwhich the indicator flag hasbeen dropped, as previously described.

While this invention has been described with reference to particularembodiments in a particular environment, various changes may be apparentto one skilled in the art and the invention is therefore not to belimited to such embodiments or environment except as set forth in theappended claims.

What is claimed is:

l. Doffing apparatus for strand processing equipment comprising, meansfor longitudinally advancing a strand at a strand processing positionand taking the strand up on a bobbin while currently imparting to thestrand a particular range of transverse alternating motion, means fordoffing the bobbin at said position, sensing means including first meansproviding various outputs and a particular output, said particularoutput being produced in response to the transverse motion of saidstrand, and second means for differentiating between said particularoutput and said various outputs and being responsive to said particularoutput to control the doffing means.

2. Apparatus as set forth in claim 1 wherein said first means providessaid particular output as a fluctuating signal, and said second meanscomprises filter means and control means, said filter means passes saidfluctuating signal, and said control means is responsive to saidfluctuating signal to provide a control signal for regulating operationof the doffing means.

3. Apparatus as set forth in claim 2 wherein said sensing means includesthird means for determining whether the strand is in operationalcondition to be advanced and when the strand is in operational conditionfor providing a second control signal, and means responsive to receivingsaid second control signal and not receiving the first said controlsignal for controlling operation of the doffing means to doff thebobbin.

4. Apparatus as set forth in claim 3 wherein said fluctuating signal hasa component within particular amplitude and frequency ranges, and saidfirst means provides said fluctuating signal in the form of a signalhaving a component within said ranges.

5. Apparatus as set forth in claim 1 wherein said first means comprisesphototransducer means.

6. Apparatus as set forth in claim 5 wherein said phototransducer meanscomprises a single photosensitive area for receiving an image of thetransverse motion of the strand.

7. Apparatus as set forth in claim 5 wherein said phototransducer meanscomprises a plurality of photosensitive areas for receiving an image ofthe transverse motion of the strand, and said areas are positioned sothat at least one of said areas receives the image of only a limitedportion of the transverse span of the transverse motion of the strandwhen said areas receive said image to provide said fluctuating signal.

8. Apparatus as set forth in claim 7 wherein said areas are spaced apartin the direction of said transverse motion of said image a distance lessthan the transverse span of the image as received by the areas.

9. Apparatus as set forth in claim 8 wherein said phototransducer meanscomprises a photon'ansducer having a single photosensitive zone having aplurality of photosensitive areas of greater sensitivity than otherphotosensitive areas intervening therebetween.

10. Apparatus as set forth in claim 8 wherein said phototransducer meanscomprises a plurality of spaced apart phototransducers each having oneof said photosensitive areas.

11. Apparatus as set forth in claim 5 including at least a second strandprocessing position arranged with said first mentioned strand processingposition, said doffing means being operable to doff the bobbin at eitherof said positions, said advancing means being operable to advance astrand at each of said positions while concurrently imparting to saidstrands a particular range of transverse alternating motion, means foractuating said first means to scan said positions and provide saidvarious outputs in response to said scanning, and said second meansregulating operation of said dofiing means to selectively doff thebobbin at the position being scanned in response to an output from thelast said position.

12. Apparatus as set forth in claim 11 wherein the doffing meanscomprises a tender and means mounting the tender and the positions forrelative movement, operating means for providing said relative movementand for stopping said relative movement with said tender proximate anyof said positions, said first means being mounted on said tender forscanning said positions, and said second means regulating operation ofsaid operating means for providing and stopping said relative movement.

13. Apparatus as set forth in claim 12 wherein said sensing meansincludes third means for determining whether the strand is inoperational condition to be advanced and when the strand is inoperational condition for providing a second control signal, and meansresponsive to receiving said second control signal and not receiving thefirst said control signal for controlling operation of the doffing meansto dofi the bobbin at the position being scanned.

. 14. A method of dofiing strand processing apparatus having a positionat which a strand is advanced onto a bobbin during operation of theapparatus and mechanism for doffing a bobbin at the position comprisingthe steps of; longitudinally advancing the strand at the position whileconcurrently imparting to the strand a particular range of transversealternating motion, providing various outputs and a particular output,said particular output being provided in response to said transversemotion of said strand, and differentiating between said particularoutputs and said various outputs and controlling the operation of thedoffing mechanism by said particular output.

15. A method as set forth in claim 14 wherein the step of providingvarious outputs includes providing said particular output as afluctuating signal, and the step of differentiating includes passingsaid fluctuating signal and responsive thereto providing a controlsignal for regulating operation of the doffing mechanism.

16. A method as set forth in claim including the step of determiningwhether the strand is in operational condition to be advanced and whenthe strand is in operational condition providing a further controlsignal, and regulating operation of the doffing mechanism in response tosaid further control signal and the absence of the first mentionedcontrol signal.

17. A method as set forth in claim 16 wherein the apparatus includes aplurality of strand processing positions at each of which a strand isadvanced onto a bobbin, and the dolfing mechanism is operable fordoffing the bobbin at any of the

1. Doffing apparatus for strand processing equipment comprising, meansfor longitudinally advancing a strand at a strand processing positionand taking the strand up on a bobbin while currently imparting to thestrand a particular range of transverse alternating motion, means fordoffing the bobbin at said position, sensing means including first meansproviding various outputs and a particular output, said particularoutput being produced in response to the transverse motion of saidstrand, and second means for differentiating between said particularoutput and said various outputs and being responsive to said particularoutput to control the doffing means.
 2. Apparatus as set forth in claim1 wherein said first means provides said particular output as afluctuating signal, and said second means comprises filter means andcontrol means, said filter means passes said fluctuating signal, andsaid control means is responsive to said fluctuating signal to provide acontrol signal for regulating operation of the doffing means. 3.Apparatus as set forth in claim 2 wherein said sensing means includesthird means for determining whether the strand is in operationalcondition to be advanced and when the strand is in operational conditionfor providing a second control signal, and means responsive to receivingsaid second control signal and not reCeiving the first said controlsignal for controlling operation of the doffing means to doff thebobbin.
 4. Apparatus as set forth in claim 3 wherein said fluctuatingsignal has a component within particular amplitude and frequency ranges,and said first means provides said fluctuating signal in the form of asignal having a component within said ranges.
 5. Apparatus as set forthin claim 1 wherein said first means comprises phototransducer means. 6.Apparatus as set forth in claim 5 wherein said phototransducer meanscomprises a single photosensitive area for receiving an image of thetransverse motion of the strand.
 7. Apparatus as set forth in claim 5wherein said phototransducer means comprises a plurality ofphotosensitive areas for receiving an image of the transverse motion ofthe strand, and said areas are positioned so that at least one of saidareas receives the image of only a limited portion of the transversespan of the transverse motion of the strand when said areas receive saidimage to provide said fluctuating signal.
 8. Apparatus as set forth inclaim 7 wherein said areas are spaced apart in the direction of saidtransverse motion of said image a distance less than the transverse spanof the image as received by the areas.
 9. Apparatus as set forth inclaim 8 wherein said phototransducer means comprises a phototransducerhaving a single photosensitive zone having a plurality of photosensitiveareas of greater sensitivity than other photosensitive areas interveningtherebetween.
 10. Apparatus as set forth in claim 8 wherein saidphototransducer means comprises a plurality of spaced apartphototransducers each having one of said photosensitive areas. 11.Apparatus as set forth in claim 5 including at least a second strandprocessing position arranged with said first mentioned strand processingposition, said doffing means being operable to doff the bobbin at eitherof said positions, said advancing means being operable to advance astrand at each of said positions while concurrently imparting to saidstrands a particular range of transverse alternating motion, means foractuating said first means to scan said positions and provide saidvarious outputs in response to said scanning, and said second meansregulating operation of said doffing means to selectively doff thebobbin at the position being scanned in response to an output from thelast said position.
 12. Apparatus as set forth in claim 11 wherein thedoffing means comprises a tender and means mounting the tender and thepositions for relative movement, operating means for providing saidrelative movement and for stopping said relative movement with saidtender proximate any of said positions, said first means being mountedon said tender for scanning said positions, and said second meansregulating operation of said operating means for providing and stoppingsaid relative movement.
 13. Apparatus as set forth in claim 12 whereinsaid sensing means includes third means for determining whether thestrand is in operational condition to be advanced and when the strand isin operational condition for providing a second control signal, andmeans responsive to receiving said second control signal and notreceiving the first said control signal for controlling operation of thedoffing means to doff the bobbin at the position being scanned.
 14. Amethod of doffing strand processing apparatus having a position at whicha strand is advanced onto a bobbin during operation of the apparatus andmechanism for doffing a bobbin at the position comprising the steps of;longitudinally advancing the strand at the position while concurrentlyimparting to the strand a particular range of transverse alternatingmotion, providing various outputs and a particular output, saidparticular output being provided in response to said transverse motionof said strand, and differentiating between said particular outputs andsaid various outputs and controlling the operation of the doffingmechanism by saId particular output.
 15. A method as set forth in claim14 wherein the step of providing various outputs includes providing saidparticular output as a fluctuating signal, and the step ofdifferentiating includes passing said fluctuating signal and responsivethereto providing a control signal for regulating operation of thedoffing mechanism.
 16. A method as set forth in claim 15 including thestep of determining whether the strand is in operational condition to beadvanced and when the strand is in operational condition providing afurther control signal, and regulating operation of the doffingmechanism in response to said further control signal and the absence ofthe first mentioned control signal.
 17. A method as set forth in claim16 wherein the apparatus includes a plurality of strand processingpositions at each of which a strand is advanced onto a bobbin, and thedoffing mechanism is operable for doffing the bobbin at any of thepositions, and wherein the step of advancing includes longitudinallyadvancing the strands at their respective positions and concurrentlytherewith imparting a particular range transverse alternating motion tothe strands, and the step of sensing includes scanning the positions andresponsive to scanning each position providing said various outputs, andresponsive to said various outputs from the position being scannedregulating operation of the doffing mechanism to selectively doff thebobbin at the position being scanned.